macOS: 12.1
Architecture: ARM64 (M1)
Shield Version: v1.2
Issue
After installing Shield and approving the System Extension I tried to start it via the drop down menu. However when I click Start I get the following.

Fix
Grant "Shield System Extension" Full Disk Access in System Preferences.
Request
Could you make the error message more descriptive?
If Shield needs Full Disk Access (FDA) it would be useful to display a message telling users to grant FDA. I believe some of the Objective-See tools have logic to detect if FDA has been granted and show a screen with instructions if it has not.